“Stiffeners” are used in the aircraft industry to reinforce or stiffen outer skins used on fuselage sections, wings, fins and similar structures. In some cases, the stiffeners, which may be stringers, are formed of composite materials and are attached to composite skins using structural adhesives that form bonded joints. Stringers may be relatively long in certain applications, such as wing structures, requiring that the stringers be precured in order to provide them with sufficient stiffness that allows them to be handled and placed in the desired position on the skin. These precured stringers are bonded to the skin, and in some cases, may require additional fastening using discrete fasteners.
The use of precured stringers requires cure tooling, vacuum bagging and autoclave operations which may increase the recurring cost associated with production of aircraft. Additionally, the use of structural adhesives to attach the stringers to the skin results in bonded joints which may present challenges in production, may add aircraft weight and in some cases, may be difficult to inspect.
Accordingly, there is a need for a method and apparatus for forming and installing stringers on a skin which reduce or eliminate the problems discussed above.